Tree display contains empty grey boxes/buttons

Problem/Motivation

Display contains empty grey box/buttons

Steps to reproduce

I created a hierarchy of taxonomy terms and displayed them using the tree widget. However, the display has some empty grey boxes above each term. Please see attached screen capture. I also see a <div> displaying the empty grey box: <div class="no-term-reference-tree-button"></div>

I'm not sure if this is a bug - but I don't think it should look like that? I'm using Drupal 11.1.5. Thank you!